The Get Code button is disabled after customer enter an random code and click register button

Problem

The Get Code button is disabled.

How to reproduced

1. Go to https://staging.jihulab.com/users/sign_up
2. Just fill the each input.
3. Enter the Get Code input directly with 111111.
4. Click Register button.

Actually result

1. 404 page is shown
2. Back to previous page. The Get Code button is disabled, until user edit/re-enter an mobile number